Zero Sequence Current Protection for Shunt Reactor with Auxiliary Winding System Inter-turn Fault

Shunt reactor with auxiliary winding system can compensate line capacitive reactive power and provide power for switching station. There is large air gap in the iron core, thus the coupling relationship between shunt reactor winding and auxiliary winding is weak. According to the special structure of shunt reactor with auxiliary winding system, equivalent circuit of shunt reactor with auxiliary winding system is researched in this paper. Shunt reactor with auxiliary winding system inter-turn protection based on zero sequence differential current is proposed, on the basis of fixed relationship between shunt reactor winding zero sequence current and auxiliary winding zero sequence current when fault occurred outside the zone. The conclusion of prototype protection device dynamic simulation test shows that this protection principle is current protection without voltage information and voltage transformer, and protection setting doesn’t need manual calculation work, and has high sensitivity for slight inter-turn fault.